package com.ftwj.demo.utils.image;


import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;

/**
 * 	缩略图生成工具
 */
public class ThumbnailGenerator {
	
	/**
	 * @param originalFile    原图路径
	 * @param thumbnailFile   缩略图路径
	 * @param thumbWidth      宽度
	 * @param thumbHeight     高度
	 * @param quality         质量
	 * @version 1.0
	 */
	public void transform(String originalFile, String thumbnailFile, int thumbWidth, int thumbHeight, int quality) throws Exception {
		Image image = javax.imageio.ImageIO.read(new File(originalFile));
	    
	    double thumbRatio = (double)thumbWidth / (double)thumbHeight;
	    int imageWidth    = image.getWidth(null);
	    int imageHeight   = image.getHeight(null);
	    double imageRatio = (double)imageWidth / (double)imageHeight;
	    if (thumbRatio < imageRatio) {
	    	thumbHeight = (int)(thumbWidth / imageRatio);
	    } 
	    else {
	      	thumbWidth = (int)(thumbHeight * imageRatio);
	    }
	    
		if(imageWidth < thumbWidth && imageHeight < thumbHeight){
			thumbWidth = imageWidth;
			thumbHeight = imageHeight;
		}else if(imageWidth < thumbWidth) {
			thumbWidth = imageWidth;
		}else if(imageHeight < thumbHeight) {
			thumbHeight = imageHeight;
		}

	    BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
	    Graphics2D graphics2D = thumbImage.createGraphics();
	    graphics2D.setBackground(Color.WHITE);
    	graphics2D.setPaint(Color.WHITE); 
    	graphics2D.fillRect(0, 0, thumbWidth, thumbHeight);
	    graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
	    graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
	    
		javax.imageio.ImageIO.write(thumbImage, "JPG", new File(thumbnailFile));
	}
}
